Two-cycle internal combustion engine with improved fuel induction means



R. C. HEIDNER ET AL TWO-CYCLE INTERNAL COMBUSTION ENGINE WITH IMPROVEDFUEL INDUCTION MEANS May 15, 1956 4 Sheets-Sheet 1 Filed May 15, 1952INVENTORS film-men C. HE/DHER WILFORD 8. BURKETT KENNETH R. /K EZ BY W wATTORNEY May 15, 1956 R. c. HEIDNER ETAL TWO-CYCLE INTERNAL COMBUSTIONENGINE WITH IMPROVED FUEL INDUCTION MEANS 4 SheetsSheet 2 Filed May 15,1952 INVENTORS RICHARD C. HE/DNER W/LFORD B-BURKETT KENNETH R. PIKEATTORNEY M y 1 1956 R. c. HEIDNER ET AL 2,745,390

TWO-CYCLE INTERNAL COMBUSTION ENGINE WITH IMPROVED FUEL. INDUCTION MEANSFiled May 15, 1952 4 Sheets-Sheet 3 i LE s F l e. 5 mmvrozes RICHARD C.Hes/0mm W/LFQRD 5. BURKETT KENNETH R. PIKE.

By 4). W

ATTORNEY May 15, 1956 R. c. HEIDNER ET AL 2,745,390

TWO-CYCLE INTERNAL COMBUSTION ENGINE WITH IMPROVED FUEL INDUCTION MEANSFiled May 15, 1952 4 Sheets-Sheet 4 Fl'a. 4

JNVENTORS RICHARD C. HEIDNER WILFORD B. BURKETT KENNETH R. 1

BY a).

ATTORNEY United States Patent TWO-CYCLE INTERNAL COMBUSTION ENGINE WITHIMPROVED FUEL INDUCTION MEANS Richard C. Heidner and Kenneth R. Pike,Hartford, Wis., and Wilford B. Burkett, Los Angeles, Calif., assignorsto West Bend Aluminum Co., West Bend, Wis., a corporation of WisconsinApplication May 15, 1952, Serial No. 287,912

7 Claims. (Cl. 12373) This invention relates to improvements intwo-cycle internal combustion engines and particularly to the inductionof a combustible mixture into the combustion chamber.

It has been the practice in this type of engine to mix oil with the fueland force the combustible mixture from the carbureter into the crankcase on the up or compression stroke and then pump such mixture from thecrank case through the intake port into the combustion chamber on thedown or explosion stroke. Because of this the combustible mixturecontains vaporized lubricating oil which has been carried through thecrank case. If a lubricating oil containing additives such as adetergent is used the spark plug will be quickly fouled by the depositof a conductive film which shorts out the plug. To avoid such foulingoil containing no such additives must be used. This means, in the caseof the Armed Forces and other large users of both two-cycle andfourcycle internal combustion engines, that supplies of both types oflubricating oils must be available. Such dual supply is not economicalor practical. The operators must be instructed as to which type of oilis to be used in a particular engine and even with such instructionmistakes are frequent.

It is an object of this invention, therefore, to provide a two-cycleinternal combustion engine which can successfully operate withlubricating oil containing additives without the consequent fouling ofspark plugs.

This object is obtained by separating the crank case with its pulsatingpressure from an induction chamber directly connected with the intakeport of the engine by a flexible diaphragm which is resistant andnon-permeable to gasoline and oil in liquid or vapor state. Theinduction chamber is connected with the carbureter or other source ofcombustible material by check valves preventing back-flow to suchcarbureter or source. As pressure increases in the crank case on thedown stroke the diaphragm will flex to force the combustible mixture inthe induction chamber through the intake port into the combustionchamber. On the compression stroke pressure in the crank case is reducedto less than atmospheric pressure and atmospheric pressure will forcethe combustible mixture from the carbureter or other source into theinduction chamber. Such chamber is then charged and in readiness for thedownstroke. Thus the atmosphere in the crank case, which may containvaporized or liquid oil, is never mixed with the incoming combustiblemixture. Hence no oil will mix with incoming combustible mixture andthereby reach the combustion chamber of the engine to foul the sparkplug.

Different ways of supporting the flexible diaphragm to obtain thelongest life will be hereafter described. Such flexible diaphragm may beadjusted as to stroke to control the volume of the charge. With suchdiaphragm it is also possible to use a fuel pump operated thereby toinject metered quantities of raw fuel into the induction chamber whereit is admixed with air. The induction chamber thus acts as a carbureter.

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The novel features which are considered characteristic of the inventionare set forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of specificembodiments when read in connection with the accompanying drawings inwhich:

Fig. 1 is a sectional view of a two-cycle internal combustion engineembodying the present invention;

Fig. 2 is a view similiar to the view of Fig. 1 showing a modificationof the invention;

Fig. 3 is a view partly in section and partly in elevation taken fromline 33 of Fig. 1;

Fig. 4 is a sectional view of a two-cycle internal combustion engineembodying another modification of the invention; and

Fig. 5 is a fragmentary sectional view of a fuel induction chamberembodying still another modification of the present invention.

With the exception of the novel devices by which fuel is induced intothe combustion chamber, the engine shown in Figs. 1 to 3 is ofwell-known construction. It is a single cylinder two-cycle air-cooledinternal combustion engine of the type adapted for use in out-boardmotors. However, the same design of engine may be used with its shaft inhorizontal position by changing the position of the oil-collecting sump.

Such engine has a cylinder in which is reciprocally guided a piston 12operatively connected to a crank shaft 14. The cylinder has a combustionchamber 16 with inlet ports 18 leading thereto. The crank shaft 14operates in a crank case 20 and its outer end carries animpeller-flywheel 22 rotatable in a housing 24.

The engine is lubricated by a pressure system which has a reservoir 26and an oil pump 28. The pump delivers oil under pressure to an opening30 in a plain bearing 32. An opening 34 in the crank shaft 14 is movedinto communication with the opening 30 when the piston is about half waythrough a stroke. At this time the pressure in the crank case isapproximately equal to atmospheric pressure. The opening 34 is connectedby passageways to the connecting rod and wrist pin bearings. Thereservoir 26 is connected with a collecting opening 36 whichcommunicates with a slot 38 in the crank shaft at about the same time asthe openings 38 and 34 are in communication. Thus at each revolution ofthe engine the pump 28 forces oil into the bearings. However, the crankcase pressure can reach the pump 28 and reservoir 26 only when the crankcase pressure is substantially atmospheric pressure, thus avoiding backpressures detrimental to the operation of the system.

During operation of the engine, the crank case 29 will contain anatmosphere which includes vaporized and liquid oil. In this engine thepulsating pressures in the crank case are utilized to induce acombustible mixture into the combustion chamber 16 without permittingsuch vaporized or liquid oil from entering such combustion chamber withthe combustible mixture. This is accomplished by providing a pressurizedchamber 40 connected with the crank case 20 and an induction chamber 42connected with the intake ports 18, such chambers being separated by aflexible diaphragm 44 which constitutes a wall of each chamber.

In the modification illustrated in Figs. 1 and 3 the pressurized chamber40 is below the diaphragm 44 and is formed by a circular bearing cage 46mounted on the cylinder 10 concentric with the crank shaft 14. A centralhub 48 of this cage provides the support for the plain bearing 32 and anannular shoulder 50 for holding the inner edge of the diaphragm.Adjacent this shoulder and arranged angularly thereabout are apluralityv of ports 52 leading to the crank case 20. The cage 46 has anoffset 54 (see Fig. 3) defining a passage 56 in alinement with theintake ports 18 and communicating with the induction chamber 42. Theouter periphery of the diaphragm 44 seats on a flange 58 on the cage 4-6and on the offset 54 and the inner periphery seats on the shoulder 59.It has an opening coextensive with the passage 56 to provide freetransfer from the chamber 42. The inner edge of such opening is securedto'such' flange by. an insert 60 fastened to such flange and fittedwithin a recessed passage 69 in the cover. A gasket 62, placed betweenthe cage 4i! and the seating surfaces of the cylinder 10, is cut away soas not to obstruct the passage 56.

The induction chamber 42 is placed above the diaphragm 44 and is formedby a cover 64 apertured to fit over the hub 48 and rest on the bearingcage 46. Such cover has an inner shoulder 66 positioned opposite to theannular shoulder 50 to engage and hold the inner periphery of thediaphragm 44 between such shoulders. The cover also has an offset 68(see Fig. 3) complemental to the offset 54 and containing a passage 69providing a connection between the induction chamber 42 and the passage56 whereby such chamber is directly connected with the intake ports 18.Ahollow arm 70 projecting from the cover 64 provides a support for areed plate 72 and manifold 74 and forms a passage for combustiblemixture from such manifold to the induction chamber 42. Suitableapertured pads 76 adapted to receive fastening bolts are spacedannularly about the cover 64 and the bearing cage 46 to clamp themtogether and create a tight outer seal for the diaphragm 44. The innerseal for such diaphragm is made tight by screws 78 extending between theshoulders 50 and 66. The reed plate 72 is of well-known design and actsas a check valve permitting inward flow to the induction chamber 42 butpreventing outward flow therefrom.

The diaphragm 44 is flexed from its inner to its outer extremes oftravel in synchronism with the pulsating pressure created in the crankcase by the reciprocal motion of the piston 12. In some engines thisdiaphragm will be flexed approximately four thousand times per minute.The material must therefore be strong enough to take such rapid flexingwithout cracking or breaking. It has been found that a nylon fabricmoulded in a synthetic. oil-resistant rubber provides ample strength andis resistant to oil. Such diaphragm maybe as thin as .010 to .12". Inorder to have flexing without stretching of the diaphragm it is providedintermediate its peripheries with annular convolutions 80 containingenough material to provide the necessary elongation without detrimentalstretching of such material. The edges of the shoulders 54 and 66,flange 58 and its complementary surface on cover 64 may all be curved tolengthen the curve about which the diaphragm flexes to prevent cracking.

It has been found desirable to provide backing up supports for thediaphragm at its outer limits of flexing. Such supports are provided bycurved surfaces 82 on the pressurized chamber and induction chamber 42.These surfaces may be provided with scallops, indicated generally at 84,to prevent a large unbroken area of surface-to-surface contact betweenthe diaphragm and such supporting surfaces. This prevents the diaphragmfrom sticking to the backing up surfaces thereby preventing its properflexing in synchronism with the motor oper the pressure therein,especially after passing the midat the mid-stroke the diaphragm 44 willhave pressures on each side thereof equalized and be in the neutral orcentral position shown in Fig. 1. During the movement of the diaphragmfrom the upper to the central position the cubic volume of the inductionchamber 42 has increased taking in combustible mixture through the reedplate 72. As the compression stroke continues past the mid-stroke, thepressure in the crank case 2% drops be-,

low atmospheric pressure and the diaphragm 44 is flexed fully downwardlyto its lower limit by atmospheric pressure with the consequent inductionof still more combustible mixture into the induction chamber 42. As theresult of continuous piston movement each time the piston 12 moves fromthe top of its stroke to the bottom of its stroke the diaphragm 44 willbe flexed from fully down to fully up position and the induction chamberbeing fully charged will deliver a full complement of combustiblemixture to the combustion chamber 16. Upon subsequent compression andignition the engine will start operation with a rapid repetition of theforegoing sequences of operations.

' Experimentation has developed that there is a tendency to accumulatepressures in the crank case 26 duringstroke or other convenient positionwhich communicates with the exterior of the cylinder. Another small port88 is made in the wall of the piston 12 and located so that it will bein momentary alinement withthe port 88 as the piston reciprocates. Thuseach time the piston reciprocates the crank case is momentarilyconnected with atmospheric pressure and pressure therein will be broughtback to atmospheric pressure.

In the modification shown in Figs. 1 and 3 the pressurized chamber isbelow the diaphragm while in the modification shown in Fig. 2 thepressurized chamber is above the flexible diaphragm. In the modificationillustrated in Fig. 2 the induction chamber 42 is below the diaphragm 96and formed by a bearing cage 90 which seats on the cylinder insubstantially the same manner as the bearing cage 46 of themodifications of Figs. 1 and 3. This cage also has a hub 92 for supportof the bearing 32,

v a shoulder 94 for forming an inner seal, and spaced ports 98communicating with the crank case 20. An inner flange 109 and an outerflange 102 on the bearing cage 90 provide support for the innerperiphery and outer periphery respectively of the diaphragm 96. Theinner periphery of the diaphragm issecured to the inner flange by a ring194 screwed to such inner flange. Passages 106 in the-cage 90 lead fromthe induction chamber 42 to the inlet ports 18. A gasket 108 isinterposed between the bearing cage 90 and the adjacent parts of thecylinder to form a proper seal.

The pressurized chamber 40 in this modification is placed above thediaphragm 96 and is formed by a cover 110. This coverfits over the hub92 and has a shoulder 112 in sealing relationship with the shoulder 94and an outer flange 114 opposite'the flange 102-and engaging thediaphragm 96 therebetween. In this modification the As the piston 12moves toward the support for the reed plate and manifold, as indicatedat 116, is made a part of the bearing cage 90 rather than the cover. Inother aspects the two modifications are substantially the same and bothoperate in substantially the same way. The diaphragm 96 has a moresymmetrical shape than the diaphragm 44 but still is provided withconvolutions 80 of identical construction. Both the pressurized chamber40 and the induction chamber 42 have backing-up surfaces 82 and scallops84 identical with those in the first modification. In the modificationof Fig. 2 there is some possibility of liquid oil collecting on thesurface of the diaphragm because of the pressurized chamber being abovesuch diaphragm. However, since such diaphragm is rapidly flexed such oilwill be dispersed and changed from liquid to vaporized state duringoperation. An offsetting advantage is the more direct communicationbetween the induction chamber 42 and the intake ports 18 which assistsin the induction of combustible fuel into the combustion chamber.

In the modification shown in Fig. 4 the pressurized chamber 40 and theinduction chamber 42 are positioned radially outwardly from the side ofthe cylinder 10 in alinement with the intake openings 18. The bearingcage 120 has a projecting body 121 forming the pressurized chamber 40and providing a port 122 leading to the crank case 20. This body has aflange 124 which provides a seat for the diaphragm 118. The inductionchamber 42 is formed by a cover 126 which has a flange 128 clamping thediaphragm 118 against the flange 124. This cover provides a passage 130leading to the intake ports 118. In this modification reed valves 132 ofa design well known to those skilled in this art are mounted directly onthe wall of the cover to let combustible mixture enter into theinduction chamber 42 from an intake manifold 134. An adjustment forregulating the length of the stroke of the diaphragm 118 is obtained bya disc 136 positioned within the pressurized chamber 40 on the end of ascrew 138. This disc limits the leftward flexing of the diaphragm 118and hence controls the volume of combustible mixture induced into theinduction chamber 42 on such stroke. The positioning of disc 136 mightalso be controlled by a governor and thus automatically control thespeed of the engine. In all other aspects the operation of the inductiondevice is substantially the same as that of the other modificationsheretofore described.

in Fig. there is shown a modification of an induction device similar tothat described in the modification shown in Fig. 4 with the exceptionthat liquid fuel is delivered into the induction chamber 42 where it ismixed with air. The induction device thus acts as a carburetor. Toaccomplish the delivery of liquid fuel a hollow piston rod 140 has itsinner end suitably secured to the central part of the diaphragm 118 andthe opening therein communicates with the induction chamber 42. Theopening at such inner end is covered by a reed valve 139 which flexes tolet liquid enter into the induction chamber when the diaphragm is movedto the left. At its outer end the piston rod 140 has a piston 142operable in a cylinder 144 connected to a source of liquid fuel 146through a port 148 closed by a reed valve 150. When pressure in thepressurized chamber 40 drops below atmospheric the piston 142 willtravel toward the left as viewed in Fig. 5 and force liquid fuel withinthe cylinder 144 through the hollow piston rod and through the reedvalve 139 into the induction chamber 42. At the same time air will beinduced through an air intake manifold 152 and the reed valve 132 intothe induction chamber 42 where it will be mixed with the liquid fuel.When the pressure rises in the pressurized chamber 40 from belowatmospheric pressure to atmospheric pressure and above, the diaphragm118 will be flexed to the right forcing the combustible mixture throughthe passage 130 into the intake ports 118. At the same time the piston142 will be moved to the right lowering the pressure within the cylinder144 and causing liquid fuel to enter therein through the port 148 andreed valve 150. v The cylinder I 144 is thus charged and ready for thenext repetition of the sequence of operation.

It is desirable to regulate the length of the stroke of the diaphragm118 to control the volume of liquid fuel delivered with each stroke.This is done by a hollow threaded screw 154 in which the piston rod isslidably mounted. The inner end of such screw engages the piston rodmounting fixture on the diaphragm 118 to determine its leftwardmovement. The smaller the leftward stroke the smaller the amount ofliquid fuel which will be pumped into the induction chamber.

In all of the modifications the essential characteristic of theinvention is the separating of the atmosphere within the crank case fromthe combustible mixture being induced into the combustion chamber toprevent including with such combustion mixture vaporized oil from thecrank case. The use of a flexible diaphragm separating a pressurizedchamber connected to the crank case and an induction chamber connectedto the source of combustible mixture eliminates the necessity of usingexpensive valves and timing mechanism required in four-cycle engines.

Although only several embodiments of the invention are shown anddescribed herein it will be understood that this application is intendedto cover such other changes or modifications as come within the spiritof the invention or scope of the following claims.

We claim:

1. In a two-cycle internal combustion engine, a crankcase, a crankshaftoperably mounted in said case, a piston operatively associated with saidcrankshaft, a combustion chamber, an inlet port in said combustionchamber, a bearing for said crankshaft, a pressurized chamber encirclingsaid bearing and connected with said crankcase, an induction chamberencircling said bearing and connected with said inlet port, a flexibleimpervious diaphragm encircling said bearing and separating saidpressurizing chamber and said induction chamber, and means for supplyingcombustible mixture to said induction chamber.

2. In a two-cycle internal combustion engine, a crank case, a combustionchamber, an inlet port for said combustion chamber, a pressurizingchamber connected with said crankcase, a flexible diaphragm imperviousto oil vap'or forming a Wall of said chamber whereby said diaphragm ispulsated by the pulsating pressure in said crankcase, an inductionchamber connected to said inlet port, :a fuel pump operated by saiddiaphragm and connected with said induction chamber to supply liquidfuel to said induction chamber, a source of air connected to saidinduction chamber, and check valve means preventing the escape ofpressure from said induction cham her to said source, said flexiblediaphragm forming a wall of said induction chamber whereby pressurevariations in said pressurizing chamber are transmitted to saidinduction chamber to charge said combustion chamber.

3. In a two-cycle internal combustion engine, a crank case, a combustionchamber, an inlet port for said combustion chamber, a pressurizingchamber connected with said crank case, a flexible diaphragm imperviousto oil vapor forming a wall of said chamber whereby said diaphragm ispulsated by the pulsating pressure in said crank case, an inductionchamber connected to said inlet port, a hollow piston rod connected withsaid flexible diaphragm with the opening in said rod communicating withsaid induction chamber, a reed valve carried by said diaphragm normallyclosing .the inner end of said opening in said piston rod, a piston onthe outer end of said rod, a cylinder connected with a source of liquidfuel, said piston reciprocating in said cylinder, a check valve etweensaid source and said cylinder whereby movement of said diaphragm causessaid piston to pump liquid fuel into said induction chamber, and meansfor inducber, a bearing cage for said crank shaft and forming avpressurized chamber encircling said shaft and connected with said crankcase, a cover for said pressurized chamber forming an induction chamberencircling said shaft and connected with said inlet port, a flexiblediaphragm interposed between said bearing cage and said cover toseparate said pressurizing chamber and said induct-ion chamber, andmeans for supplying combustible mixture to said induction chamber. V i g5; Ina two-cycle internal combustion, engine, a crank case, a crankshaft operably mounted in said case, a piston operatively associatedWith said crank shaft, a combustion chamber, an inlet port in saidcombustion chamber, a bearing cage for said crank shaft and forming aninduction chamber encircling said shaft and connected With saidinlet'port, a cover for said induction chamber forming a pressurizedchamber encircling said shaft and connected with said crank case, aflexible diaphragm in- :terposed between said bearing cage and saidcover to sepaton, an induction chamber connected with said inlet port,

a pressurizing chamber connected with said crank case,4a flexiblediaphragm between said chambers and forming a wall of each wherebychanges of pressure in said pressurizing chamber cause flexing of saiddiaphragm to change the-volumetric capacity of said induction chamber,said'cylinder having a vent leading to atmosphere and normallycoveredby. said piston, said piston having 1 a vent in momentaryregistration with said first ventduring reciprocation of said piston andleading to said crank 7 case whereby said crank case is momentarilyvented to atmosphere to prevent accumulation therein of pressures aboveor below atmosphere, and means for supplying a combustible mixture tosaid induction chamber under the influence of the change of volumetriccapacity of said induction chamber. I

7. In a mechanism comprising a cylinder'having a piston reciprocaltherein, a crank case, a fuel induction chamber operated by changes ofpressure in said crank vent pressures .in said crank case fromaccumulating sufii-. ciently above or below atmospheric pressure to stop-op- BlfiiiOfl of said fuel induction chamber.

References Cited in the file of this patent UNlTED STATES PATENTS-Norway Mar. 12, 1945

